Running Poorly At Idle

Not sure from here.

Could be sucking fuel through the accelerator pump circuit, maybe. Often the check-ball weight gets lost when people work on the YF carb, or could be crud, or a worn out diaphragm.

 

You think it would be possible for me to plug that hole with my finger and see if the irregular idle goes away?

 

Why not, if you can?
I really can't be sure from the picture which hole, vent, or jet that may be. There are several.

If you don't have a Factory Service Manual, you really should get one. And if you search on line you can find detailed service bulletins for the Carter YF.


Throttle Bushings and Idle Quality
While the YF is pretty much indestructible, it will wear over time. Throttle shaft to throttle body would have originally been 0.004 to 0.006 inch. Normal wear up to about 0.009 is acceptable. Wear of 0.010 or more is going to start showing up as poor idle quality. As the clearance of throttle body to throttle shaft increases, unmetered air will enter the intake manifold, causing a lean idle. Tuners will compensate for this lean condition by increasing the idle mixture. This in turn, can cause a hesitation or bog in transition from the idle to the main metering circuit. We are often asked about bushing kits, but we are hesitant to sell them. If it is determined (use a dial indicator) that throttle bushings are to be installed they MUST be correctly installed. One may NOT use a reamer (or drill) and ream completely through the throttle body and then install bushings, as this will create an internal vacuum leak resulting in a higher than normal idle (not adjustable). Visualize looking down the air intake of the carburetor. You see a round throttle bore. If bushings are installed with the use of a reamer, the square edge of the end of the bushing will leave two small triangles on each side of the throttle plate that allows a small amount of air to slide by the throttle plate. This is unacceptable.

To correctly install bushings, obtain a bar of the same diameter as the throttle shaft, and use this bar as a pilot to align the throttle body in the vise of your vertical mill (a good heavy-duty drill press may be used). Remove the pilot and using the appropriate mill or drill for your bushing, mill or drill into the throttle shaft hole to about 0.050 inch from the throttle bore. Leave this 0.050 inch to retain the original throttle bore curvature. Install the bushing by using a bushing pilot and press the bushing into the throttle body. Do the other side in like fashion. NOW is the time for the reamer (ream completely through the throttle body), which should be 0.004 to 0.006 inch larger than the diameter of the throttle shaft (original specification).







see the website of The Carburetor Shop,

 

That is the accelerator port. Just back up stream is a passage which should have a weighted needle or a steel check ball and weight on top. If the ball/needle doesn’t sit flush with the metered aperture when at idle the carb will not have a solid stream upon acceleration. There is a test you can perform to check this. With the carb off of the motor and the choke/bowl cover and gasket removed, look for the brass or steel weight in the passage and it should be limited in travel by a circular spring on top. Taking care to not lose that spring, manipulate the throttle with one hand and keep a finger over the port in carb throat, and watch for fuel to spurt out. If fuel stays in the passage for at least 10 seconds above the weight the check ball/needle is correct. If not, use a brass drift the same size as the ball/weight and gently tamp it down with a few GENTLE blows with a very small hammer. Re-check.

 

Scoutpilot is the expert. Listen to him.

I will note, not all YFs have the retaining "circular spring" on the top of the weight, in my experience, but they function the same.

 

I drained the gas into a clean 5 gallon bucket and this is what I got



I filled the tank about 1 and 1/2 months ago so I wouldn't have thought it would look like thisi am not seeing anything that looks like water in it but it was just drained so maybe it needs to sit for a while to see it

 

that's just a reflection

 

I took apart the carb to try and check the metering rod adjustment and I'm not an expert on it but it seems adjusted fine. checked the float level, it was 3/8 so I changed it to 5/16. I did scoutpilots recommendation of the 10 second test for the check ball and it was good ( the check ball leads to the hole that I was referring to earlier about that tiny hole that irregularly squirts fuel while my engine runs like it is) I looked at the diaphragm and it seemed pliable and I didn't see any holes.

After draining all the gas from the tank, the lines, and the pump and the carb, I then put in 2 gallons of fresh from the gas station gas. and its still doing it.

but before I messed with the carb I could get the engine to die when I screwed in the mixture screw all the way, now when its fully seated engine still is running the same aka poorly but still running

I resprayed starting fluid and I couldn't get any changes in idle speed even at the base of the carb

at this point I think I have tried or adjust everything except for the valve but the engine tested with good compression so I think that would indicate valves aren't out of spec.

I don't fully understand the carb and how it works but I am wondering if that sporadic fuel squirting into the carb that's coming from the check ball is whats making my idle vary

I do have a solex carb that was on the jeep when I got it maybe tomorrow I should swap it back on to see if anything changes

http://vid1174.photobucket.com/albums/r605/blysct/20160522_200739_zpssspewboy.mp4

 

the dwell rpm device I am using says to double the 8 cylinder scale if you cant read it on the machine.

but I do have 2 of these dwell tachs and they both say something different so I'm not sure which one to trust. ones an old sears and ones an old snap on that takes a 9v battery

 

apparently it had recoded sideways so it would be easier to view this one on your smartphone and flip the screen

 

That video is helpful. Your motor is “Surging” or “Hunting”. #1 cause is a vacuum leak somewhere. #2 cause is fuel pressure/flow that is not steady. #3 cause is faulty ignition. Some component is breaking down intermittently. #4 cause is a clogged PCV system. The PCV ties in with the vacuum.
Can you dial the idle down to 700 without it dying? Where is your vacuum gauge?

 

Vacuum gauge. Use one.

 

Another video WITH a vacuum gauge too this time. gauge shows late timing but no matter which direction i turn the distributor i cant get it to move the needle to normal engine and playing with the mixture screw doesnt get it into green and screwing the mixture all the way in wont kill the motor like i thought it should

 

That vacuum reading tells me the valve guides need attention. You can check this by gradually increasing the RPM. If the needle goes steady you can assume the guides are worn. When was the last valve job?

 

By valve job do you mean like grinding lapping or simply adjustment? I haven't adjusted the valves for a few years other than that I don't know

 

Gaskets looked ok to reuse, I didn't do a full teardown of the carb just took the top off to adjust float. I checked metering rod by backing out idle screw and pushing down on the tall post thing and wiggling the metering rod up and down and it seemed to be seated

 

Valve guides.
If you don't have a FSM, you should get one.

 

I have a FSM. I'm just not sure if guides is something I can tackle myself or not. Unless the guides came out I don't think that's my issue because it was working perfectly for years. One day everything was perfect idles like a kitten. Then suddenly the next day it's doing this. I would think guides would fail over time. Not instantly.

Is there a way I can check for this? I had a tool you screw into spark plug hole to keep valves shut. While you remove the keepers. Is there a way to use this to check for this?